Your lawyer?

Britain still uses lots of cheques. I couldn't get the money from sale of shares other than by cheque.
No direct transfer to an account in continental Europe. Modern age hasn't arrived in British banks.

Except in Canada where it still feels like 1960 in many ways.

But as others have said, depositing a Canadian cheque made out in $C to a UK bank account (in person, the old fashioned way) isn't a problem at all. I do it frequently.

You should be able to deposit your Canadian cheque to your UK bank account without any issues.

You should also be able to deposit your Canadian cheque to your Canadian bank account without the need for any intermediaries. When I wanted to deposit a UK cheque to my UK bank account (while in Canada), I simply posted it to an HQ cheque clearing address (your bank can provide you with the address details) and the staff deposited for me. All that was needed was the cheque and a short letter to instruct them to deposit it into the account XXXX with sort code XXXX. I cannot see why this does not work with Canadian banks - just check with your Canadian bank about it. No need for intermediaries or anyone involved, and you can then wait for the best exchange rate before you transfer your money between accounts.

EDIT: a lot of banks allow depositing cheques through their e-banking apps, but beware, it's usually only for small amounts. E.g Lloyds only allows up to 500gbp cheques to be deposited via the app, and that limit cannot be lifted under any circumstances.